Primary hepatic leiomyosarcoma diagnosed after right hepatectomy: A rare case report.

This is a case report of primary hepatic leiomyosarcoma. An 82-year-old Japanese man presented with fever and mild abdominal pain. Laboratory testing demonstrated marked inflammation and substantial elevations of CA19-9 and PIVKA-II. Computed tomography revealed a large necrotic mass in the right hepatic lobe with gallbladder wall thickening. Gallbladder cancer invading the liver with abscess formation was suspected, but a definitive preoperative diagnosis could not be established. Right hepatectomy and cholecystectomy achieved an R0 resection. Histopathological examination showed fascicles of spindle cells, extensive necrosis, and high mitotic activity. Immunohistochemical staining was positive for α-smooth muscle actin and h-caldesmon and negative for desmin and epithelial markers, confirming primary hepatic leiomyosarcoma. Although abscess-like presentations have been reported, the combination of severe inflammatory findings, markedly elevated CA19-9 and PIVKA-II, and gallbladder wall thickening was unusual and contributed to diagnostic confusion. This case emphasizes the need to consider primary hepatic leiomyosarcoma in the differential diagnosis of a large necrotic hepatic mass and supports complete surgical resection when technically feasible.